Novel CdS Hole-Blocking Layer for Photostable Perovskite Solar Cells

Area of Science:

• Materials Science
• Photovoltaics
• Renewable Energy

Background:

• Perovskite solar cells (PSCs) show great potential but suffer from stability issues hindering commercialization.
• The compact titanium dioxide (TiO2) layer, traditionally used, is suspected to contribute to photoinduced degradation due to oxygen vacancies.
• Research on improving PSC stability, particularly photostability, remains less explored compared to efficiency advancements.

Purpose of the Study:

• To develop a novel hole-blocking layer to enhance the photostability of perovskite solar cells (PSCs).
• To replace the conventional TiO2 layer with a cadmium sulfide (CdS) layer to mitigate photoinduced degradation mechanisms.
• To investigate the impact of the CdS layer on charge-carrier dynamics and overall device performance under illumination.

Main Methods:

• Fabrication of PSCs utilizing a CdS hole-blocking layer as a replacement for the standard TiO2 layer.
• Performance and stability testing of both CdS-based and TiO2-based PSCs under continuous sunlight illumination.
• Electrochemical impedance spectroscopy (EIS), open-circuit voltage decay, and time-resolved photoluminescence (TRPL) decay measurements to analyze charge-transfer characteristics.

Main Results:

• PSCs with the CdS layer maintained over 90% of their initial efficiency after 12 hours of continuous sunlight illumination.
• PSCs with the traditional TiO2 layer retained only 18% of their initial efficiency under identical conditions.
• CdS PSCs exhibited negligible degradation in charge-carrier dynamics, while TiO2 PSCs showed increased recombination, charge-transfer resistance, and reduced charge extraction.

Conclusions:

• The novel CdS hole-blocking layer significantly enhances the photostability of perovskite solar cells.
• Replacing TiO2 with CdS effectively suppresses photoinduced degradation pathways, leading to improved long-term operational stability.
• The CdS layer offers a promising strategy for developing commercially viable and durable perovskite solar cells.